Global Warming and the Courts

Published: July 8, 2006

In a move that has caused both delight and apprehension among those who worry about global warming, the Supreme Court has agreed to rule next fall on whether the Environmental Protection Agency has the authority under the Clean Air Act to regulate carbon dioxide and other greenhouse gases. The case is among the most important environmental disputes ever to come before the court.

The outcome will have much to say about whether the country will be able to act more aggressively on a problem with potentially grave consequences for the earth and its inhabitants. It could also determine whether states that have acted on their own to limit global warming emissions from vehicles -- as California and 10 other states have done -- can proceed without fear of a federal veto.

President Bush has advanced many reasons for not pressing for strong controls on greenhouse gas emissions from vehicles, power plants and other industrial sources. But his ace in the hole has been the claim that the federal government has no authority to regulate greenhouse gases.

The case turns largely on a simple reading of the Clean Air Act. The administration argues that the act mentions carbon dioxide only in passing, and that if Congress had been truly worried about global warming it would have given the gases that cause it more emphasis and instructed the E.P.A. to take aggressive steps to control them, as it did with sulfur dioxide and other pollutants. The administration argues further that the science on global warming is too ''uncertain'' to justify anything more than a voluntary effort to deal with it.

The plaintiffs -- a formidable collection of state governments and environmental groups -- argue that the plain language of the Clean Air Act gives the government jurisdiction over ''any air pollutant'' that threatens ''public health or welfare'' and, further, that ''welfare'' specifically includes effects on climate and weather. This interpretation of the act was first set forth by President Clinton's E.P.A. and stood as agency policy until Mr. Bush reversed it (without consulting his own E.P.A.) in 2001.

As for the science that the administration finds so shaky, the plaintiffs will argue that the science has grown steadily more persuasive since the Clean Air Act was last revised in 1990; that the administration has cherry-picked arguments about details while ignoring the vast preponderance of the evidence; and that the consensus among mainstream scientists -- a consensus reinforced by a recent National Academy of Sciences report -- is that the earth is inexorably heating up and that industrial emissions are largely responsible.

This is a case of global importance, not least because America's failure to act decisively has discouraged the rest of the world from acting decisively. On the face of it, the law plainly gives the government the power to regulate greenhouse gases. A ruling that tells the administration that it has that power does not mean that it will actually use it. But it will no longer be able to hide behind a legal fiction.